Collaborative Research: Host race Formation Among Southern Hawthorn-infesting Populations of Rhagoletis Pomonella

这项研究项目的目标是了解苹果的主要害虫--苹果蝇Rhagoltis pomonella如何形成专门捕食美国南部不同种类的原生山楂食用植物的种群。与蝗虫等昆虫不同的是，一个给定物种的所有个体都可以并确实吃各种各样的食用植物，而苹果蝇和类似的昆虫形成了当地的种群(称为寄主小种)，只以一种或几种植物的果实为食。为了了解它们是如何做到这一点的，将对攻击美国南部不同种类山楂的苍蝇种群进行测试，以确定：1)它们是否优先倾向于它们滋生的山楂物种果实的化学气味--这就是苍蝇如何在自然界中寻找寄主植物交配并产卵的；2)苍蝇生命周期的时间是否适应了不同山楂树结果的时间差异--一些南方山楂在季节早期(5月)和一些南方山楂果实(10月-11月)，以及3)气味反应和生命周期的任何观察到的差异都是基于遗传的程度。这项研究的更广泛的影响是多方面的，具有重要的应用和基本好处。昆虫经常将它们的食物转向新的作物。苹果蝇就是一个典型的例子，在过去的100年里，它从几乎没有商业价值的原生山楂转移到了具有很大经济价值的引进苹果。有关这一过程如何发生的信息将由对南方山楂蝇的研究提供，这是更好地管理害虫所必需的。例如，苹果上的红山楂果蝇会被红色山楂的气味驱赶，反之亦然，这就导致了在各种南方山楂中可能发现更好的天然驱避性气味的可能性。该项目还具有基本的科学意义，因为转移到新植物上可能会触发许多宿主特有的昆虫的物种形成。最后，该项目将通过帮助整合地方、社区和大学层面的科学培训和教育，提供重要的额外社会效益

The goal of this research project is to understand how the apple maggot fly, Rhagoletis pomonella, a major pest of apples, can form populations that specialize on different species of its native hawthorn food plants in the southern United States. Unlike insects such as grasshoppers, where all individuals of a given species can and do eat a wide range of food plants, the apple maggot and similar insects form local populations (termed "host races") that feed within the fruits of only one or a few plant species. To understand how they do this, fly populations attacking different species of hawthorns in the southern United States will be tested to determine: 1) if they preferentially orient toward the chemical odor of the fruit of the hawthorn species they infest--this is how the flies find their host plants in nature to mate on and lay eggs into fruit, 2) if the timing of the life cycle of the flies is adapted to differences in when the various hawthorn trees fruit--some southern hawthorns fruit very early in the season (May) and some late (October-November), and 3) the degree to which any observed differences in odor response and life cycle are genetically based. The broader impacts of the research are multi-faceted, having both important applied and basic benefits. Insects frequently shift their feeding to new crops. The apple maggot fly is a classic example, having shifted in the last 100 years from native hawthorns of little commercial interest to introduced apples of great economic value. Information about how this process occurs, which will be provided by research on southern hawthorn flies, is needed for better management of pests. For example, Rhagoletis pomonella flies from apple are repelled by the odor of red hawthorn, and vice versa, leading to the possibility that even better natural repellent odors might be found among the various southern hawthorn species. The project is also of basic scientific interest because shifts onto novel plants may serve as a trigger for speciation for many host specific insects. Finally, the project will provide important additional societal benefits by helping integrate science training and education across the local, community, and university levels